There has been conventionally used a centrifugal compressor for feeding a process gas under pressure in various types of plants. There is a type of centrifugal compressor which injects a washing liquid into a flow path which is formed thereinside.
This type of centrifugal compressor is able to remove dirt and thermal reaction products adhered or deposited on the flow path by using the washing liquid, thus making it possible to recover the performance deteriorated by the adhered or deposited products.
As the above-described centrifugal compressor which injects a washing liquid, there is available, for example, a centrifugal compressor which uses a spray-type nozzle as an injection device for injecting the washing liquid. The injection device is placed, for example, at the top portion of a return vane arranged in a flow path, that is, the injection device is disposed outside in the radial direction of the return vane to atomize the washing liquid and inject the liquid toward the flow path (refer to, for example, Patent Document 1, Patent Document 2, Patent Document 3 and Patent Document 4).